This invention relates to fuel injection devices. More specifically, it relates to fuel injection nozzles of the so-called "zero sac" variety.
Prior art of possible relevance includes the following U.S. Pat. Nos. 3,039,701 issued June 19, 1962 to Carlisle; 3,093,317 issued June 11, 1963 to Simmons et al; and 3,578,249 issued May 11, 1971 to Davis.
Increasing concern in recent years over emissions from internal combustion engines has resulted in an increase in the popularity of so-called "zero sac" fuel injection nozzles in engines employing fuel injection inasmuch as they tend to promote more complete combustion and, therefore, minimize the emission of hydrocarbons. Fuel injection nozzles of the non-zero sac type allow a small volume of fuel to remain in the nozzle between the usual check valve and the outlet end of the spray orifices. Such fuel does not participate in the combustion process but, rather, tends to evaporate during later stages of the combustion cycle due to exposure to the hot gases of combustion. As a consequence, such vaporized fuel will be emitted from the engine in an unburned state, i.e., as hydrocarbons.
One type of injection nozzle known in the art utilizing a pintle valve, as, for example, the construction disclosed in the above identified Simmons et al patent, eliminates the problem in that a valve seats against the outlet end of the fuel delivery port, preventing any fuel from being directly exposed to the hot gases of combustion. However, such nozzles produce but one fuel jet rather than several. As a result, much swirl is required in the combustion chamber of the engine to achieve good mixing of air with the fuel to obtain optimum combustion.
In engines having minimal swirl, i.e., quiescent engines, such nozzles cannot be utilized unless more than one is employed since good mixing cannot be obtained with but a single nozzle with the result that combustion conditions are not optimal with the result that considerable unburned fuel will be emitted as hydrocarbons.
Consequently, such nozzles cannot be advantageously employed with all engine designs or must be multiplied in number with the resulting attendant expense.